Instrument for hemoglobin determination having two filters to match the spectral curve of oxyhemoglobin



Sept. 13, 1949. M. G. BROWN 2,481,567

INSTRUMENT FOR HEMOGLOBIN DETERMINATION HAVING TWO FILTERS TO MATCH THE I SPECTRAL CURVE OF OXYHEMOGLQBIN Filed Dec. 26, 1945 B 5 Sheets-Sheet 1 Fig.2.

INVENTOR. MORDEN G. BROWN WQW ATTORNEY Sept. 13, 1949. M. G. BROWN 2,481,567

, INSTRUMENT FOR HEMOGLOBIN DETERMINATION I HAVING TWO FILTERS TO MATCH THE SPECTRAL CURVE 0F OXYHEMOGLOBIN Filed Dec. 26, 1945 5 Sheets-Sheet 2 GREEN FILTER (moomso EKQo.

WRA'I'TEN "14; EQUIVALENT WRATTEN 15 ANDwRmENM cew sssflcosm BLUE GLASS) DEPTH 2: 3.0 .5

OXYHEMOGLOBYN {ab} 12.0 %"%00 m9 DEPTH=OJ25 INVENTOR. MORDEN 6'. BROWN HTTOR IVE Y Sept. 13, 1949. M. G. BROWN 2,481,567

INSTRUMENT FOR HEMOGLOBIN DETERMINATION HAVING TWO FILTERS TO MATCH THE SPECTRAL CURVE OF OXYHEMOGLOBIN Filed Dec. 26, 1945 5 Sheets-Sheet 5 n1 Q I Z g F *1 I 2 I V) I5 z N I I a: I r Q "20 9 I l a l 1 l 2.5 l I I z I I s.o L

WAVELENGTH, y

---- GREEN FILTER (MODIFIED EK Co.

WRATTEN *74; EQUWALENT WRATTEME AND WR TTEN EA uRAmuM emss DEDTHxaoF OXYHEMOGLOBIN {Nb}: \2 o a'vfwmk DEPTH: o. 25%

INVENTOR.

MORDEN 6. BROWN 8 T TOR/VEV Sept. 13, 1949. M. G. BROWN 2,481,567

INSTRUMENT FOR HEMOGLOBIN DETERMINATION HAVING TWO FILTERS TO MATCH THE SPECTRAL CURVE OF OXYHEMOGLOBIN Filed Dec. 26, 1945 5 Sheets-Sheet 4 OGMS Hb/dll.

4ems Hb/df.

BRIGHTNESS (LOGARITHM I c $CALE) WAVE LENGTH, Mmuwcaoms MQRDEN GI. BROWN ATTORNEY 6 I INVENTOR.

Sept. 13, 1949. M. G. BROWN 2,48

INSTRUMENT FOR HEMOGLOBIN DETERMINATION HAVING TWO FILTERS TO MATCH THE SPECTRAL CURVE 0F OXYHEMOG-LOBi-E Filed Dad. 26, 1945 5 Sheets-Sheet 5 mm mm 14 TTOE/VEY Patented Sept. 13, 1949 INSTRUMENT MINATION R HAVING TWO FILTERS, ,1

MATCH THE SPECTRAL CURVE OF 'OXY HEMOGLOBIN Morden G. Brown, Williamsville, :N. ,.Y.,: assignmto American Optical Companyr. S'Outhbridge; Mass., a-voluntary association of Massachusetts Application December 26, 1945;8erial-No. ear-.22?

(c1. .ss '14:)

8 Claims.

This invention relates to an instrument for accurate determination of hemoglobin in the blood.

One of the primary functions of the blood is to transport oxygen'from the lungs to all tissues of the body. This vitallyimportant oxygen carrying capacity is best measuredby measurement of the concentration of the red pigment, hemoglobin, with which the oxygen is loosely combined during transport.

It has been found advantageous to measure hemoglobin concentration by colorimetric methods. Generally 'such a determination is not made with the blood as drawn from the patient; but instead the sampleused is'som'e derivative such as oxyhemoglobin, carbon-monoxide hemoglobin, acid hematin, pyridine hemochromogen, or cyanmethmoglobin. Although the most convenient of these derivatives-to use is oxyhemoglobin (due to the fact that this compound is formed upon simple exposure to air), the other derivatives have been widely used. One reason for use of these other less convenient derivatives is that it has been found diflicult to match the oxyhemo globin sample by a permanent standard. I believe that this difiiculty is due to the fact that the absorption'spe'ctra' of ox'yhemoglobin is very irregular. The standard, such as a glass standard, has generally been'charact erized by spectrophotometric curves which-are different from those for oxyhemoglobin. Inother words, the observer is attempting to compare two illuminated areas which do not transmit equally in the same portions of the spectrum. The observer is therefore calling upon his retina to evaluate colors. It is well known that observers vary in sensitivity to red and green light. Since it is the ratio of the amounts of red and' green light which largely determines the apparent color of blood, considerable variations in settings have been found by different observers when making color matches between blood and the glass used as a standard of comparison.

Accordingly, an'object ofmy invention is to provide an instrument in accordance with which determination of theconcentration of oxyhemoglobin is arrived at thru comparison of the brightness of a standard with the brightness of the sample of oxyhemoglobin.

In accordance with the -present invention, the errors due to theabovementioned color vision characteristics have been overcome by selecting for a standarda glass which, in a portion at least of the spectrum, does not substantially deviate in its spectral curve-from-t-he spectral curve of oXyhemoglobim-an'dby limiting the light transmitted 'to'the-observers eYeto-the above mentioned portionof the spectrum. Moreover, the portion of the" spectrum selected includes the -2 yellow -and green*wher' athe'ssensitivitysof the .eye is the greatest;

This .results in smaking it possible to :arrange side by side for comparison-by the observer two patches of light which doi not vary substantially from each other excepts-n brightness. Therefore, the observer is merely called-upon :to determine whether these .patchestof l-ighthave'eq'ual brightness'; and thr'eforekthematching of theintensh ties orbrightnesses is not sub-ject'to'the handicap of a difference in-ic'olor.

In the drawings which illustrate. diagrammati cally an opticalsystemmsefuliin carrying out the method which I'--hav;e::described; and in whicha'n illustrative form-eof' instrument is shown:

Fig. 1' is-a perspective view iof such an optical system;

.Fig. ,2' is-xa-side-view vof,;theioptical:system;

Fig. 3 is amend-"viewthereof-takenfronrthe right side .ofi'Fig-l 2 I Fig. 4 is axgraph'showing'zthe absorption-curve of ox'yhemoglobmisuperimposediontheabsorption curveof a ityipicalglass which I use ac' cordance withtmy invention;

Fig. 5- is aasimilargraph' :showingthe absorption curive .ofoxyhemoglobinrsuperimposed on the absorptiongcurvepof a different glass which Iuse in accordance-zwith'my'invention;-

Fig. 6'is .aegraphishowing the absorption curves of Fig.4 as mod-ified by a filte'rof the type that I employ, bynthe-color sensitivity of the eye, and by the emission characteristics-ofthe clamp;

Fig.- '7 isga; longitudinalncentra'l secitionthrough aform of instrument ,for determiningythe concentration of-oxyhemoglobin'in' accordance with my in-ventiony v Fig. 8 is a central transverse section of theiinstrume-nt-shown in Fig. 7.

M-y 'invention may: :be embodiedin instruments of variousconstruction having .a bloodchamber and a standardarranged to be'viewed simul-' taneously the observenzso that a" comparison betweenthein-tensit-ies of -;the :two "may be found. Then by a variation i-n' the-thickness of one .of the two relative to" the other, matching of intensityAis-attained'and za reading found. Such instruments-are which the thickness of the blood chamber is :varied. Itis' more convenient-however; to i make the standard in the form of an optical wedge soas-i to vary" the intensity of the -.staridardrel ative' to the intensity of the sample of-i oiryhmog'lobin:

An instrumento'f theJatter' character is'illu's trated in the patent-"of iGr'a'jdisa-r" and Brown; 2,3 96,2691granted-"March 1946." The' principle of an} instrument thischai' actei will now" be on with Figs; -1, -2-,fand- 3*of light seureesnewn' diagramin y'a Fig- 3') in" eeeperanen with a repeater rn' evemyclmminates edicts-mg plate II. This plate |.v is sufiiciently diffusing as to act as a secondary source of illumination.

The standard l2, which in this instrument is; in the form of a wedge of glass, is arranged closely 7 adjacent the blood chamber. l3, Both of these are illuminated by the diffusing plate II. For

reasons of compactness, the "intensities of the two are viewed by means of a reflector; this reflector preferably taking the form of a bi-prism M which deviates the light'received from the standard and specimen respectivelyinto the viewing means 20. The patches of light observed thru the viewing means 20 should be separated by a line of unperceived width; and this is accomplished by the bi-prism l4, since the entrance'surface's l and l6 are angularly related so as to deviate toward each other'the two fields or areas of brightness to be matched. Moreover, after being reflected by the surface I1, these fields or areas are further deviated by theangularly with aneyepiece lens 22. The power of this lens 22 is such as to bring into focus for the observer the apertures 24 and 24a, for the wedge and chamber 49v may be positioned (a speoimen'holder or blood chamberl3 containing a specimen which preferably has been first hemolized. This may,

for example, be accomplished in the manner described in, my, application Serial No; 627,873, filed November 10-, 1945;": The frame member 46 is also shaped to provide; in conjunction with the partition 42; an elongated longitudinally disposed guideway 56 locatedi'at the opposite side of said central vertical plane. In the guideway 561s positioned the wedge-shaped standard I 2 for movement along'the guideway as will further be explained.

The frame member 46 is also provided with a horizontal portion 52, which carries laterally spaced integral upstandingflanges 53' having bearings 54 formed therein'for pivotally'mountw specimen respectively, and moreparticularly the V dividing line between these apertures.

As pointed out in the above identified patent, it is convenient to arrange the elongate wedge I2 for movement as indicated by the double headed arrow 26 parallel to the optical axis of the eyepiece lens 22 since this axis is the long dimension of the instrument. Moreover, the wedge is arranged beside the specimen holder or blood chamber i3 with its upper surface in the same plane as the specimen holder. One of the entrance surfaces of the bi-prism receives light from the standard and theother entrance sur face receives light from the specimen.

An improved form of instrument for the observation of the juxtaposed patches of brightness, which is the subject of an application Serial No. 637,230, Morden G. Brown and Harry F. Lundberg filed December 26, 1945, is shown in Figures 7 and 8.

The casing or housing oi the instrument is' divided into two parts 30 and 3| detachably secured together by resilient clips 32. The part 363 is provided with a pair of cells and of the dry cell flashlight variety for supplying current to the electric lamp 9 provided with the reflector l0. The circuit including the battery of cells and the lamp is under control of push button 39. The part 3| is provided adjacent opposite ends thereof withintegral lugs 40 for receiving the screws 4| which serve to secure apartition 42 in place, this partition corresponding roughly to the dividing line between parts 30 and 3|. The partition .42 is apertured adjacent its opposite ends to receive the bent ends of the resilient clips 32, and isprovided with a central window 24 glazed with the diffusing plate. I I. A unitary frame member 46, preferably formed as a die casting, is mounted on the partition 42 and secured in place by screws 41. The frame member 46 is shaped to provide ,a central chamber 49 (see Fig, 8) at one side ofthe longitudinal vertiqalcentra pla e o the ins ment. In the ing a spring retainer 55. This spring retainer; when in lowered position; engages the bi-prism reflector M to: resiliently press the reflector against its seat on the frame member 46. This seat is apertured (as shown in Fig. 8) and is in overlying relation. to the standard I2 and; blood chamber l3. [The aperture in the seat is divided by a rib 5'! (integral with member 46) which also closely fits a longitudinal slot in the prism. Y W 4 a j The frame member 4615 also provided with an elongated forward portion 59 which is Channel-shaped and provided with rills 6|] to avoid reflections toward the observer. Asimilar non: reflecting wall portion 6| is formed upon the inside of the part 3| to cooperate with the channel-shaped portion 59 in providing a 'sighting tube 32 along which the; observer may look in using the instrument. The sighting tube 62 has an end wall :63" integral with member 46 and provided with an aperture 64 aligned with the reflector I l. The observer sights along the tube 62 through the, eyepiece lens 22 and filter 2|. The wedge-shaped (standard It may be cemented orotherwise secured along the joints 66 to an elongated slide or'carrir 61 which is arranged to flt within the guideway 50 and be guided at 68 upon the upper surface of the partition 42 so that it may be moved'therealong when the device is in operation. An elongated spring 73 has its opposite ends positioned in a recess in the carrier 61 and its central portion bears standard l2 to be-moved longitudinally until a matching relation with the 63 has been obtained. 7 V

In order that the observer may compare inspecimen in holder tensities andmay not be handicapped by having to evaluate difierences in color, a standard -|2 is employed which is made of a glass whose spectral curve matches closely the spectral curve of oxyhemoglobin in the portion of the spectrum transmitted by the filter'ZL I have found that cobalt glass and uranium glass meet these requirements. By cobalt glass I mean a glass whose spectral curve is characterized by rapidly decreasing transmission ,with increasing wave length as 530 millimicrons is approached, an in-.

This arm 12, together further rapid decrease in :transmission. iGenerally this decrease. continues to about ".595 mil limicrons, followed by somewhat .of; an increase in -tra3nsmis'si0n followed by ganoth'er ::decrease around 645 millimicrons, aftemwhich-an increase in transmission occurs; but as well .known, not all. cobalt glassesiare made -fmm the a "same ingredients: indeed, addition productsare intentionally put in=where it isfidesiledto vary the absorption in certain. portions 'of (the, spectrum such .as in the 're'dandkblue v.portionsof the spectrum, and: thereforea .cobalt glass as I use the term may have aaspect'ralkcurve which. does not exhibit true minimumand'maximum: at 595 andt645 millimicronsrespectively. The minimum of transmission at 1 about 154.0 :millirnicrons, the maximum at about 565 :andthe-ldecrease toward about fi95iare acharacteristic, while'fas above pointed out, variations in: other portions of the spectrum are not materialto myginvention.

Fig. 4 shows in unbroken lineethe. spectral curve of oxyhemoglobinmand inxdot and-dash .linethe spectralgcurve of-:.aCor.ning':Cilass.Works glass sold as #5551 (Cobalt BluetGlass).

spectral curveof .a.-.green:-filter (Modified EastmanKo'dak Co. Wratten it- 74) is.:also shown in Fig.4. .to indicate which: portions of the spectrum are prevented from reaching: the observers eye by this-:g'reen filter. "This: is: the green. filter which I prefers-to use at "2|.as above. explained. It will be noted that. themyellow and green-portions of .the'spectrum which: are "passed. .by the filter 2 I correspond. to: the. wavelengths of maximum sensitivity of the: eye.

Fig-'6 shows for three-concentrations, namely 4,12-and 20 gramsof oxyhemoglobiniper deciliter ata thickness 'of 0.152 mm. 'and 'for zero absorption of eitheroxyhemoglobin orcglass-the respective spectral curves for oxyheinoglobin and for the corresponding thickness of "Corning Glass orksaglass #5551 as modified byalg-reen filter (Modified Eastman Kodak. Go. Wratten #74) by the color sensitivityrof thereyeandiby the emission' characteristicsrof the: lamp: 9.

In Fig. 6, the'spect'ral'. curves for the various concentrations of oxyhemoglobin as thus modified areshownrin' full lines and: the z modified spectral curves for glass #5551 are shown. in dash. lines.

'Another'glass which is equally suitable for the purposes of :my 'inventiom-but: which is not shown in the drawings,--is;sold':by;-Kopp Glass Inc. :as Electric Lunar White. Although-theword Cobalt? isnot includ'edain thename roi Lthis glass,

*its spectral curve which is=quite5 similar to that of Corning Glass Works #5551 indicates that it contains cobalt, and in; 1 any eventy it .is. included within the term Cobalt lglass as that-tennis employed herein.

ALStlll. further glassiwhich is suitable for the purposes of my invention is uranium glass. A typical uranium glasshaaa spectral curve which is shown.in.Fig...,5. -This g-lassiis coloredwith uran'ous salt, and it will be notedjthatits spectral curve between 52o millimicrons ahd-580 millimicrons is quite-similarto thespeotral curve of oxyhempglobin. By uraniunpglass, as thatterm .is used inthe present specification and-claims, I 'means a glass whosespectral curve is character-;

ized by a maximum' of transmission at about 5.2-

missionwat about- 540 emillimicrons fol1owed=-by another maximum-mt transmissionzratrab'out 565 millimicrons. The uranium glass whose spectral minimum are suitable.

Both cobalt glass and uraniumfl glass, :it will be noted from Figs. 4;and;5,:haveianfabsorption curve closely approximating-the absorption curve of oxyhemoglobin except inthe 'portioniof the spectrum of longer wavelength-than about 570 millimicrons and-shorter thanaboutSlQ-millimicrons. These outer portions of the :p spectrum are substantially eliminated by.=,the-;filter. 2l ,,;for which purpose I prefer. touse.;a green"filter .which has low transmission in. the portion-ofsthe spectrum of shorter wavelength than 510,mil-1-imicrons and longer wavelength .than 57o-m ,zrmiciiQns. A gelatin filter suitable for this ;purpose is manufactured by Eastman Kodak .Co. astModified Wratten #74. An equivalent isacombinatiomof .Wratten #15 with Wratten #44. l

Accordingly, by combining ,with .a.-;standard. .of the above type which hasa spectrahcurVe-closeli! approximating the. spectral gcurve'qof aoxyhemoglobin in the yellow and ;green p0rtions.-,.of ,:.the spectrum a filter which eliminatesthememainfing portions of the spectrum, I, provide an- -irnproyed method of determining the :oxyhe moglobin con-- centration in a specimen; since thepbserver-compares intensities, and is notu-subjectttothe.-;di:tliculties arising out of hisperson-al colops ision characteristics. An instrument embodying .the principle of my inventionhasthe-importantqadvantage that it presents for comparisontwoianeas which can be observed and gcompared strictlyirom the point of View .of their .-,.br;ightnessfs o. as. -to arrive at an accurate determination @of. away,- hemoglobin content, the light-transmitted toe the eye of the observer :being restricted to. those portions of thespectrumin whichthe spcctral curve of the oxyhemoglobin does nottsubstantially de- Viate from the spectral curve,=0f, the standard employed in the, instrument. I

While I have. illustrated land. describedadatails of an instrument whichv has beemiourld adyantageous as an embodiment of my invention,-it will be understood that ,my .invention may; be otherwise embodied and..-practiced withinthe scope of the following claims. 7

Having described. invention, I claim:

1. An instrument for determining the concentration of hemoglobin intheblood.cornprisinga specimen holder for supporting afllayer Iof. oxyhemoglobin of predetermined thicknessv andfan adjustable optical wedge arranged forlsimultaneous observation of their comparativebrigjhtness through viewing means, said wedge being fornie'd of cobalt glass having an absorption curve inthe central portion of the visible-spectrum which approximates the absorption curveof-Qxyhemoglobin, and said viewing -means 'being provided with a filter for substantially absorbing-from the light used in said viewing-means the=portions-of'-the visible spectrumshorter than about 500.- millimicrons and longer than about 550 i to 5!Z-0 millimicrons.

2. An instrument for determiningstheiconcem .tration of hemoglobin-in the ,bloodrecomprising viewing means, anda :specimen -.holder=vorssapporting a layer of woxyhemoglobinzofiipredeter- ,mined thickness. and a standardvmour'ite'd in-sa'djacent relation in: the ifield: of: viewlof: said; mowing .means; said standard beingriormediofe'cobaltsglass having a spectral curve: characterized.byaazmini- :mum oftransmissionuat; abeutsfiem millimicrons with a filter substantially absorbing the portions of the visible spectrum shorter than about 500 to 510 millimicrons and longer than about550 to 570 millimicrons.

'3. An instrument for determining the concentration of hemoglobin in the blood comprising viewing means, a specimen holder for supporting oxyhemoglobin in a layer of predetermined thickness and a standard optical member mounted in adjacent relation in the field of view of said viewing means, said standard being formed of a glass having a spectral curve characterized by a'relatively low transmission at about 540 millimicrons, a relatively high transmission at about 565 millimicrons and a transmission at about 510 millimicrons relatively higher than the transmission at 565 millimicrons, and a filter in said instrument substantially absorbing the portion of the visible spectrum shorter'than about 500 to 510 millimicrons and substantially absorbing the portion of the visible spectrum longer than about 550 to 570 millimicrons.

4. An instrument for determining the concentration of hemoglobin in the blood comprising viewing means, a filter for filtering light before it reaches the operators eye, a specimen holder for supporting a quantity of oxyhemoglobin of predetermined thickness in the light path in the instrument and an optical wedge mounted in adjacent relation thereto so that the specimen and wedge will both be in the field of view of said viewing means, said wedge being adjustable for positioning a selected portion thereof adjacent said specimen holder, said wedge being formed of cobalt glass possessing spectral transmission characteristics which in the central portion of the visible spectrum approximate the transmission characteristics of oxyhemoglobin in the same region, said filter substantially absorbing the portion of the visible spectrum of shorter wave lengths than about 500 to 510 millimicrons and absorbing the portions of the visible spectrum of longer wave lengths than about 550m 570 millimicrons. 7 g

5. An instrument for determining the concentration of hemoglobin in the blood comprising viewing means, a filter for filtering light before it reaches the operators eye, a specimen holder for supporting a quantity of oxyhemoglobin of predetermined thickness in the light path in the instrument and an optical wedge mounted in adjacent relation thereto so that the specimen and wedge will both be in the field of View of said viewing means, said wedge being adjustable for positioning a selected portion thereofadjacent said specimen holder, said wedge being formed of uranium glass possessing spectral transmission characteristics which in the central portion of i the visible spectrum approximate the transmission characteristics of oxyhemoglobin'in the same region, said filter substantially absorbing the portion of the visible spectrum of shorter wave lengths than about 500 to 510 millimicrons and absorbing the portions of the portions of the visible spectrum of longer wave lengths than about 550 to 570 millimicrons.

and a maximum of transmission at about 565 V niillimicrons, said viewing means being provided 6. An instrument for determining the concen-,

tration of hemoglobin in the blood comprising a specimen holder for supporting oxyhemoglobin of predetermined thickness in the optical path of the instrument, means for viewing the brightness of the specimen, a light filter for filtering 8 the light before reaching the observers eye, and a standard opticalmember mounted'in adjacent relation to said specimen holder so that said specimen, and optical member may both be viewed by said viewing means, said standard being formed of a glass having a spectral transmission curve characterized 'by a relatively low transmission at supporting oxyhemoglobin in a predetermined substantially uniform thickness in the path of light emanating from said source, a standard optical member mounted in side by side relation to said specimen holder and also in said path of light emanating from said source, a viewing station located so as to'receive the light from said source and transmitted by the specimen in the specimen holder and by said standard, said specimen having a spectral transmission curve with a characteristic shape in that portion lying between approximately 510 and 580 millimicrons, said standard having a spectral'transmission curve with the portion between approximately 510 and 580 millimicrons simulating the shape of the corresponding portion of the spectral transmission curve of the specimen, and a filter. positioned between said source and'said viewing station and having characteristics for absorbing substantially all of the spectral transmission curve lying below 510 millimicrons and lying above 580 millimicrons.

8. An instrument for use in determining the concentration of hemoglobin in blood comprising viewing means, a specimen holder for supporting hemoglobin in a layer of predetermined thickness and a standard opticalmeans disposed in ad- Jacent relation in the field of view of said viewing means, said standardbeing in the form of a light transmitting optical wedge having a spectral curve characterized by a relatively low transmission at about 540 millimicrons, a ,relatively high transmission at about 565 millimicrons and a transmission at about 510 millimicrons relatively higher than the transmission at 565 millimicrons, and ajfilter in said instrument substantially absorbing the portion of the visible spectrum shorter than about 500 to 510 millimicrons and substantially absorbing the portion of the visible spectrum longer than about 550 to 570 millimicrons.

MORDEN G. BROWN.

REFERENCES CITED 7 The following references are of record in the file of this patent;

UNITED STATES PATENTS Name Date Dufiie Aug. 15, 1944 OTHER REFERENCES Number 

